> -----Original Message----- > From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of > Dominik Zalewski > Sent: 26 June 2015 09:59 > To: ceph-users@xxxxxxxxxxxxxx > Subject: Ceph and EnhanceIO cache > > Hi, > > I came across this blog post mentioning using EnhanceIO (fork of flashcache) > as cache for OSDs. > > http://www.sebastien-han.fr/blog/2014/10/06/ceph-and-enhanceio/ > > https://github.com/stec-inc/EnhanceIO > > I'm planning to test it with 5x 1TB HGST Travelstar 7k1000 2.5inch OSDs and > using 256GB Transcend SSD as enhanceio cache. > > I'm wondering if anyone is using EnhanceIO or others like bcache, dm-cache > with Ceph in production and what is your experience/results. Not using in production, but have been testing all of the above both caching the OSD and RBD's. If your RBD's are being used in scenarios where small sync writes are important (iscsi,database's) then caching the RBD's is almost essential. My findings:- FlashCache - Probably the best of the bunch. Has sequential override and hopefully facebook will continue to maintain it EnhanceIO - Nice that you can hot add the cache, but is likely to no longer be maintained, so risky for production DMCache - Well maintained, but biggest problem is that it only caches writes for blocks that are already in cache Bcache - Didn't really spend much time looking at this. Looks as if development activity is dying down and potential stability issues DM-WriteBoost - Great performance, really suits RBD requirements. Unfortunately the ram buffering part seems to not play safe with iSCSI use. With something like flashcache on a RBD I can max out the SSD with small sequential write IO's and it then passes them to the RBD in nice large IO's. Bursty random writes also benefit. Caching the OSD's, or more specifically a small section where the levelDB lives can greatly improve small block write performance. Flashcache is best for this as you can limit the sequential cutoff to the levelDB transaction size. DMcache is potentially an option as well. You can probably halve OSD latency by doing this. > > Thanks > > Dominik _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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